Sprockets ISO 9 tooth

looking for nine tooth primary chain wheel I am a bit bigger guy not looking to set records just looking to slay some serious hills without the expense of a jack shaft kit.
any help with what exactly to look for or where to find them is greatly appreciated

thank you for the info to be honest I have been lurking for a little over a year built mine and made the choice to try the things less done.
that said is there any place to source them I am living in northern minesnowta and plan to pick up a few different front / rear chain wheels and finding what works the way I want. I have a major / minor rebuild planed. pull the motor paint the frame install random upgrades and other things must be done. lets just say I put it together because I had never seen one before, in a total of 3 days after my 5pm 3am shift. now I will proudly admit to being a chef but a mechanic? I am a better plumber lol. I have great friends and a amazing shop in town that keep the "real" motors running. forgive me but I just want to see what does what for what. ie: 40T:10T=25mph cruise.
I am #230 and pedal some of the time run without the motor some time and some times I barely petal
I guess this is because I haven't heard much in the way of our primary gear on these HT engines

use the largest sprockets possible. torque transfer is improved and as butre says...chain wear is minimized. you also have less frictional losses with larger diameters. all three are closely tied together.

thank you HeadSmess. ok so if I am understanding this correctly (feel free to correct me) but a larger drive matched with a smaller wheel sprocket is geared mostly with torque and going bigger on the wheel is more for speed. as the "zone" is achieved when you can cruise around 1/2 - 3/4 wot and when throttle is applies you should feel a pull. more importantly I feel the "zone" is achieved when cruising around 2/3 throttle and being able to dive bomb the road ditch when spotting a choice trail. my real issue is maintaining torque when doing this.

the reason you use the largest front sprocket possible is because the diameter of the sprocket is larger...liken it to a spanner on a nut... the longer the spanner...the easier it is to tighten the nut...less strain on the chain.

the chain also has to wrap around the sprocket. the larger diameter the sprocket, the less the chain has to "flex" from being straight, to being curved as it passes over the sprocket.

ie, using a tiny little 6tooth sprocket (like on those cheap 50cc pocket rockets) the chain is almost folded in half as it travels over the sprocket.

whereas with a big, 20 tooth sprocket...the chain is closer to straight.

the more the chain has to "wrap", the more friction, the more wear it receives, combine with more stress from the torque issue pointed out above, the faster the chain itself wears out.

of course, there is a limit to the sizes you can use whilst retaining the required reduction ratio AND keeping chain speed down... bigger sprockets travel further, and the chain, being heavy, tends to fling away from the sprocket.

theres also the crankcase/sprocket cover that limits just how big you can go.

its all a bit of a fiddle, therefore...just stick with the stock standard 10 tooth sprocket and play with the rear sprocket only.

11 tooth is as big a front sprocket as you can go without modifying the case. with a 12 you need to do quite a bit of dremel work. the whole chain slap thing is generally not an issue because of that. not unless your sprocket is out of alignment